The focus of the projects being carried out is to analyze the bacterial photosynthetic reaction center protein, an integral membrane protein, of known structure, that uses light energy to initiate electron and proton transfers. Theoretical projects analyze how ionization of acidic and basic side chains and redox cofactors is controlled by the protein's structure. Progress in the last year includes (1) Extensive analysis of the importance of the protein backbone for stabilizing buried charges; (2) Electrostatic analysis of the cofactor oxidation/reduction potentials in the photo- synthetic reaction centers and in cytochromes C. (3) The first direct experimental observation of the electron transfer from QA to QB by optical spectroscopy.